The question:
Having a master-details record update problem. When I have a master record (ORDERS table, in my case) with a Set of details (LINE_ITEMS in my case) and use hibernate to update the master/ORDER record, I'm getting a *second* update statement being generated:



ORDER_NUM is ORDER's primary key field, so basically, it's issuing SQL to erase the foreign-key reference field in the child.

Question is: WHY? What am I doing in my mapping that's making hibernate decide to do this?


Hibernate version:
3

Mapping documents:

Here's the mapping in Order:


Here's the primary key declaration in LineItem (though I don't see how this matters):


There is no reference to Order in LineItem's hibernate mapping.
(Note: no choice about data model or use of fields - it's someone else's database...)


The generated SQL (show_sql=true):

Hibernate: update ORDERS set APPLICANT_NUM=?, COMPLETION_DATE=?, ... (truncated)
Hibernate: update LINE_ITEM set ORDER_NUM=null where ORDER_NUM=?

It's the source/purpose of this second 'update' that is at the heart of my question.

Full stack trace of exception that occurs:

Long; no other info below stack trace in this post.

2006-05-08 22:36:35,406 [level3] WARN [http-8080-Processor24] JDBCExceptionReporter.logExceptions(71) | SQL Error: 0, SQLState: 01004
2006-05-08 22:36:35,406 [level3] ERROR [http-8080-Processor24] JDBCExceptionReporter.logExceptions(72) | Data truncation: Column set to default value; NULL supplied to NOT NULL column 'ORDER_NUM' at row 1
2006-05-08 22:36:35,468 [level3] ERROR [http-8080-Processor24] AbstractFlushingEventListener.performExecutions(299) | Could not synchronize database state with session
org.hibernate.exception.GenericJDBCException: Could not execute JDBC batch update
at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:91)
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:79)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:202)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:230)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:142)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:296)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1009)
at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:356)
at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106)
at org.springframework.orm.hibernate3.HibernateTransactionManager.doCommit(HibernateTransactionManager.java:584)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:500)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:473)
at org.springframework.transaction.interceptor.TransactionAspectSupport.doCommitTransactionAfterReturning(TransactionAspectSupport.java:266)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:170)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:176)
at $Proxy6.persistNewOrderScore(Unknown Source)
at com.xyz.manualscore.webapp.action.OrderAction.save(OrderAction.java:144)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:274)
at com.xyz.manualscore.webapp.action.BaseAction.execute(BaseAction.java:213)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:118)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Unknown Source)
Caused by: java.sql.BatchUpdateException: Data truncation: Column set to default value; NULL supplied to NOT NULL column 'ORDER_NUM' at row 1
at com.mysql.jdbc.ServerPreparedStatement.executeBatch(ServerPreparedStatement.java:647)
at org.apache.commons.dbcp.DelegatingStatement.executeBatch(DelegatingStatement.java:294)
at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:58)
at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:195)
... 46 more
2006-05-08 22:36:35,578 [level3] ERROR [http-8080-Processor24] ActionExceptionHandler.logException(147) | org.springframework.jdbc.UncategorizedSQLException: Hibernate operation: Could not execute JDBC batch update; uncategorized SQLException for SQL [update LINE_ITEM set ORDER_NUM=null where ORDER_NUM=?]; SQL state [01004]; error code [0]; Data truncation: Column set to default value; NULL supplied to NOT NULL column 'ORDER_NUM' at row 1; nested exception is java.sql.BatchUpdateException: Data truncation: Column set to default value; NULL supplied to NOT NULL column 'ORDER_NUM' at row 1
java.sql.BatchUpdateException: Data truncation: Column set to default value; NULL supplied to NOT NULL column 'ORDER_NUM' at row 1
at com.mysql.jdbc.ServerPreparedStatement.executeBatch(ServerPreparedStatement.java:647)
at org.apache.commons.dbcp.DelegatingStatement.executeBatch(DelegatingStatement.java:294)
at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:58)
at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:195)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:230)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:142)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:296)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1009)
at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:356)
at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106)
at org.springframework.orm.hibernate3.HibernateTransactionManager.doCommit(HibernateTransactionManager.java:584)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:500)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:473)
at org.springframework.transaction.interceptor.TransactionAspectSupport.doCommitTransactionAfterReturning(TransactionAspectSupport.java:266)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:170)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:176)
at $Proxy6.persistNewOrderScore(Unknown Source)
at com.xyz.manualscore.webapp.action.OrderAction.save(OrderAction.java:144)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:274)
at com.xyz.manualscore.webapp.action.BaseAction.execute(BaseAction.java:213)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:118)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Unknown Source)

Name and version of the database you are using:
MySQL

There are two problems with that mapping. First one is easy: you need a not-null="true" in the <key> element of the set.

Second one is about the key relationships. You've made the hibernate key of LINE_ITEM be a composite, but they <key> element specifies only one column. I'm surprized that that even works. Is LINE_ITEM.ITEM_NUM unique, or is it a list index? That is, does every ORDER have a LINE_ITEM row with ITEM_NUM = 1?

If ITEM_NUM is unique across the table, then it should be the only column in the id of LineItem: use ORDER_NUM only in the association back to the Order object (it doesn't matter that the column is part of the DB's primary key for the table, it'll still work).

If ITEM_NUM is repeated for every unique ORDER_NUM, then I recommend changing orderDetails from <set> to <list>, and use <key column="ORDER_NUM"> <list-index column="ITEM_NUM">.